Pressure control valve



Oct. 3. 1950 O c. s. J. MacNEll. Er Al.

PRESSURE CONTROL VALVE 2 Sheets-Sheet 1 Filed Dec. 25, 1943 Oct. 3, 1950 c. s. J. MaCNElL Er AL PRESSURE coNTRoL'vALvE 2 Sheets-Sheet 2 Filed Dec. 25, 1943 INVENTORS CHARLES 5J Mnc/vE/L a J/'N E H/NES z 3 mfzf'zgf y 44 ATTORNEYS Patented Oct. 3, 1950 UNITED STATES PATENT OFFICE PRESSURE CUNTROL VALVE Charles S. J. MacNcil, John F. Haines, Richard E.

Moore, and Howard Carson, Dayton, Ohio, assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application December 23, 1943, Serial No. 515,456

6 Claims.

a pressure control valve that will operate effi ciently and free itself from interference by foreign matter should it nd its way into the fluid medium.

Another object is to provide a control valve with means for stabilizing its action against fiutter by means of viscous damping providing re striction to high frequency motion by the urge of pressure or heavy spring force.

Other` objects contemplated include the piloting of a cylindrical pressure limiting valve with the elimination of cooking and binding of closely calibrated relatively movable parts, the counteraction of inertia effect in a centrifugally operated valve through the use of proper damping means, the provision of a control valve that will be of the simplest construction and easiest of assembly without the use of special tools, and the provision of a control valve that will maintain stable control of pressure under all operating conditions with a minimum of leakage and wear at the metering parts,

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. l is a schematic sectional view of a propeller hub and regulator of the fluid operated type illustrating the fluid circuit into which the proposed structure is adapted for connection and operation, the view being substantially as indicated by the line and arrows I-I of Fig. 2.

Fig. 2 is an elevational View of the regulator plate with its cover removed to show the relation of the control elements, it being a view substantialliT as indicated by the line and arrows 2.-2 of Fig. 1. i

Fig. 3 is an enlarged sectional view of the control valve substantially as indicated by the line and arrows 3 3 of Fig, 1.

Referring rst to Fig. 1 for a general descrip tion, 58 refers to an engine nosing or gear casn ing from which extends a rotatable shaft I2 for the driven rotation of a propeller hub I4 having a plurality of sockets i6' mounting a plurality of blades 8adapted to turn upon their individual axes for pitch adjustment'. provided with suitable bearings 28and are jour-L The blades I8 are Y the root of the-'blade I8.

(Cl. IS7-e140) nalled about a spindle 22 extending radially from the hub I4 to provide a splined extension 24 1ocated in an internal splined chamber 26\Within A piston member` 28 has internal splines working on the splined eX- tension 24 of the spindle, and external splines working on the splines of the chamber 26, and fits with a substantial fluid tight relation to divide the chamber 26 into pressure chambers 30 and 32 inward and outward of the piston 28.

' Embodied in the hub I4 and extended into the spindle 22 there are a pair of control passages 34 and 36 which open into the chambers 3U and 32 respectively at one end and communicate at the other end with control ports 38 and 40 in a governor valve assembly 42 located in a reservoir 44 provided by a regulator housing 46.

The regulator housing is usually mounted on a rear tubular extension of the hub I4, and exists in the form of an annular chamber Whose inner bounds are closed off by an adapter sleeve 48 supported by a plate 50 by means of a spacer ring 52 and screw devices 54. The plate 50 is notched at 56 to engage a lug 58 provided by a pilot plate E8 rigidly mounted on the engine nosing Hl, and provides a structure for restraining rotation of the adapter sleeve 48 but permits it to weave and wobble relative to the propeller shaft and thus to follow any eccentric movement of the regulator during rotation of the propeller. The adapter sleeve extends across the annular housing such as to have bearing engagement at 62 and 64 with the housing, and thus complete enclosure of the reservoir 44 which provides a container for the pressure operating fluid, and houses the control elements by which the pitch of the blades is changed.

Among the control elements enclosed in the reservoir there are the governor valve assembly 42, which has a pressure supply port 66 with a passage 81 in the body of the housing leading to a pump 68, and a branch 10 communicating with a control valve 12, the subject of the instant invention. The governor valve assembly 42 embraces a block mounted on the inner face of the housing and has a bore 14 vdisposed radially of the axis of propeller rotation and into which open the ports 38, 40 and 66 to be selectively controlled by a plunger 16 having lands 18 and 88 normally covering the ports 38 and 40 when the plunger is in equilibrium position. The equilibrium or balanced position of the plunger is attained by centrifugal Vforce acting upon the plunger 'lli to throw it radially outward and opposedby the constantly applied iorceof a spring 82 supported by a shelf or ledgev 84 and engaging a lever 88 pivoted at 88 to the plunger 'IB and resting upon a movable fulcrum 90. The fulcrum 98 `is mounted Aon a carriage 92 that is adapted to slide upon guide ways 94 carried by the block,

and is adapted to move to either side of the line of spring force, but for the most part is restricted during constant speed operation of the mechanism to be moved only along the outer limits of the guide ways.

Means for moving the carriage during operation of the propeller is embodied in a control ring 96 surrounding and movable axially of the adapter sleeve 48 where it is guided by the limit pins 98, its movement being effected by a plurality of high lead screws journalled in a thickened flange |02 of the adapter sleeve and the spacer ring 52 where pinions |04 of the high lead screws mesh with an internal ring gear |06 uiournalled about the spacer ring 52 and disposed between the housing flange 46 and the plate 50. The' ring Vgear |06 is provided with a lever |98 to which is attached suitable linkage ||0 connected with a manual controller I2 located in the pilots compartment. Movement of the pitch control lever in the cockpit causes the ring gear |06 to rotate the high lead screws |00 which in turn effect the axial movement of the control ring 96 and due to the shoe I |4 of the carriage 92 riding in a groove ||6 of the control ring effects movement of the fulcrum toward and from the valve plunger, thus changing the movement arms through which the spring force and centrifugal iorce act upon the valve plunger 16.

The pump 68 comprises a unit mounted in a well of the housing and embraces a pair of gears ||8 one of which is driven by a shaft |20 having a pinion |22 meshing with a toothed flange |24 on the thick portion |02 of the adapter sleeve, such that rotation of the propeller mechanism about the adapter sleeve causes the gear |22 to roll over the toothed flange |24 and eiect rotation of the meshing gears I8 that draws in fluid from the reservoir 44 through the intake pipe |26 and discharges the fluid under pressure into the pressure passage 61 from which it is expendable into the passage 10, and through the port 66 to the bore 14 of the governor valve assembly 42. Designedly, the output of the pump 68 is considerably in excess of the amount of lluid that would be permitted to ow into the ports 38 and 40 during the pitch control operations, and means are therefore provided to spill the excess over and above a maximum developed pressure back into the reservoir.

The device accomplishing the return of fluid to the reservoir and controlling the pressure developed in the iluid circuit is the pressure control valve 12 shown in its functional relation in Fig. 1, and in enlarged section in Fig. 3. The pressure control valve is in fact mounted on the housing within the reservoir somewhat as shown in Fig. 2, but for the purpose of illustration it has been otherwise shown in Fig. 1, though its inclusion within the reservoir is suggested by the dotted line showing of the reservoir 44. Communicating with the passage 10 there is a lter chamber |30 formed by the cooperation of two chambered members |32 and |34 clamping a close mesh screen |36 which acts as a permeable partition across the chamber |30, screw devices |3| holding the parts in iluid tight relation. The chamber member 32 has a port or opening |38 aligned with the passage 10 while the member |34 has an outlet opening |40 leading to the control valve 12, and the blocks or members |32 and |34 are retained in mounted relation on the housing 46 by means of appropriate screw devices |42 that operate also to hold the valve 12 in assembly with 4 l the lter unit, there being an appropriate gasket |44 disposed between the valve and filter.

For the specific structure of the pressure control valve 12, reference is now made to Fig. 3 where there is shown a tubular casing |46 having a cylindrical bore with ground surfaces |48 and |50 at opposite ends and concentrically arranged with respect to the longitudinal axis. Two apertured ears |52 are provided to facilitate mounting by means of the screw devices |42, and the outer end of the casing or that which contains the ground surface |48 is closed by an integrally formed head member |58 which renders the end of the casing leakage proof. The opposite or inner end of the casing |46 is tted with a tubular insert |60 engaging the ground surface |513 to provide a concentric ground bore |62. The tubular insert is in the nature of a sleeve that extends endwise within the casing |46 and provides three axially spaced'annular grooves |64, |66 and |68 exposed to the bore of the casing. In the grooves |64, |68 there are disposed sealing rings |10 that prevent leakage between the insert and casing. lExtending through the wall of the insert |60 there are a plurality of cross bores |12 connecting the groove |66 with the ground base |62, A snap ring |69 lodges in a groove at the open end of the casing |46 for retaining the sleeve in assembled relation with the casing, and the latter is apertured at |1| for opening the groove |66 to the outside of the casing.

The exhaust of fluid and consequently reduction of pressure through the passages |12 and |1| is controlled by a spring pressed plunger |14 housed within the casing and having portions closely fitting with the ground surfaces |46 and |62. The plunger is of substantial mass and has a head member |16 ground to closely fit within the bore |48 which acts as a pilot for movement of the plunger. Passages |11 and |19 in head |16 connect a chamber |18 between the head |16 and the closed end |58 with the cylindrical bore on the opposite side of the head |16. The head cooperates with the chamber |18 to dampen movement of the plunger and the rate of damping is controlled by the cross-sectional area of passages |11 and |19. The plunger further has a reduced or necked portion connected to a terminal head |82 by a shoulder |84 providing clearance for the flow of uid from the bore of the casing |46 to the ports |12 when exposed to the uid pressure within the casing. The total effective piston area is dened by the disc area of the terminal head |82, and may be increased or diminished by altering the diameter of the terminal head and ground bore |62. Housed within the casing |46 and disposed about the plunger |14 is a relatively stiff helical spring |86 that bears at one end against a shoulder |88 adjacent the head of the plunger and at the other end engages an end surface of the tubular insert at |98. The casing has a transverse opening |92 that opens its interior to the filter chamber when the pressure control valve is mounted in place.

The control Valve 12 is so mounted on the regulator plate that the plunger |14 will be displaced along a radius of rotation for the propeller mechanism somewhat as shown in Fig. 2, and is so disposed that the weighted head |15 will be radially outward and the terminal head or valving portion will be radially inward of the assembly.

In the normal rest position, or when the pressure of the system is low, the valve and casing will have a relation practically as shown in Fig. 3, in which the damping chamber |13 is practically collapsed, and the terminal head |82 will completely stop any now through exhaust ports |12, and be whollyon the radially outward sides thereof. The method of mounting will so couple the force of the compression spring |86 and the centrifugal force acting on the mass of the valve plunger that they will be in aiding relation to maintain the terminal head |82 in closing relation with respect to the ports |12. When the propeller is operating sucient opposition is then built up by the iiuid pressure on the effective area of the piston to move the plunger to a position for opening the ports |12 to the interior of the casing and hence to the opening |92. The direction of the force of the spring and centrifugal force applied to the plunger is illustrated by the arrow A in the various views. On reference to Fig. 2 it will be observed that the direction of these forces are radially outward, and that the discharge of liquid from the valve unit is at the radially inward end as shown in Fig, l.

It is understood rof `course that theA regulator has as many vbranches 34 and 36 of the passages from the ports 38 and 4G as there are blades on the hub and torque'units or pistons 28 for moving the blades. That is accomplished in the actual structure by extending the passages 34 and 36 well around the circumference of the hub and then tapping into those passages at |94 and |96 for uid leads to each of the torque units, substantially as shown in Fig. 2. Reference to Fig. l, therefore, should suce to depict the operation of the structure insofarias rotation c-f the propeller mechanism about the relatively fixed part 48 will effect actuation of the pump 68 to charge the pressure line 61 with fluid under pressure, which is impressed upon every element whose fluid circuit is open thereto. As shown in Fig. 1, the lter unit and pressure control valve are directly exposed to the pressure developed, as is also the governor valve assembly 42. In the illustrated setting of the Valve plunger 16 the pressure port 66 is there open to the control port 40 which leads by passage 36 to the chamber 32 on the outside end of the piston 28 for each torque unit, thechamber 3|) Aon the inside end of the piston being open through the control passage 34 and control port 38 and bore 14 a to return to the reservoir 44. Consequently the piston 28 will be moved radially inward of the axis of rotation and the blade I8 will be rotated to effect a reduction of pitch, which when accomplished sufficient to satisfy the conditions of regulation called for by the governor valve assembly will eiect return of the governor valve to the equilibrium position. The governor valve mechanism is sensitive in its operation and effects close regulation of the pitch to the extent that great changes are never required, and therefore no great amount of ow of that available is used in effecting the lregulated shift,v Continued operation of the pump 63 builds up pressure to a desired high degree which may be stored in an accumulator fo-r future use, or it may be existent only in the remaining continuously active portion of the fluid circuit, and is controlled within a predetermined high Value by the pressure control valve 12. As one example of desired pressure charge in the system, whether it be fitted with an accumulator, or existent in the Huid circuit illustrated, consider that the active circuit is charged with a pressure of 950 pounds per square inch to give a flow of 15,0Y to 1,60cubic inches per minute. Then the pressure control valve will be so designed and so mounted that the force exerted by the spring |86 and the centrifugal force acting on the plunger |14 will require the exertion of 950 pounds of pressure per square inch on the ,effective piston area before the terminal head |82 will be moved to a position to expose the ports |12 to the bore of the casing |46. While these forces are acting the iiuid pressure in the bore of the casing is being built up and exerts itself on both sides of the head |16 through the bleed passages |11 and |19, wherefore the active area of the piston opposing the spring and centrifugal force is limited substantially to the area of the terminal head. The bleed passages 11, |19 and the damping chamber |18 are suflcient to prevent quick action of the valve plunger and thus prevent hunting and flutter.

Yremove such matter that may nd its Way into the fluid medium by interposng the filter unit |311 in the pressure line, for the specific purpose of protecting the control valve 12. However, should any foreign matter pass the filter screen |36 it will not seriously affect the operation of v,the pressure control valve 12 due to the high .Spring and centrifugal force to be opposed by the piston area. In event of a chip lodging in the outlet ports |12 and tending to hold the valve ropen, the high spring and centrifugal force would act to move or shear it olf. Further, with any consequential opening of the ports |12 the relief of pressure from the bore of the casing will carry any chips outwardly into the reservoir. The piloting head of the valve plunger also insures `against cooking of the valving ports, and its mass in conjunction with the damping provisions re- =duces the inertia effect that is common with Valves with large pressure areas.

yIn the specific embodiment of the control valve 12, all critical features of the construction are concentrated about the terminal head and tubular insert, and principally in the latter; A

change in location of the exhaust ports |12, or

-a change in size of those ports, and a change in effective area of the piston or terminal head |82 can be made without scrapping of a major part of the assembly, as might be the case if the Vground base and exhaust ports were located in v4the casing 146.

Leakage from the damping chamber |18.is eliminated by the integral construction of casing |46 and head |58, thus accurately defining the damping by the bores |11,

and |19, which cannot be interfered with by the spring |86 seating on the head |16, were the clamping passages cut in the surface of the head.

Also the properties of the damping passages are lnot altered by Wear through continuo-us or frequent movement of the plunger |14, as might be the case if the damping passages were to be located on the surface of the head |16. That results in there being no substantial pressure drop on the -two sides of the head |16, which makes for controlled damping under all conditions of where the discharging iluid looses its high velocity and is discharged to the reservoir of the regu lator at a relatively low velocity. Since the groove |66 is always kept full of fluid through ports ITI, there is no mixing of air with high velocity fluid coming from |12, and hencefrothing and foaming of the fluid is prevented.

In the propeller construction under consideration, the force required for the pitch changing mechanism increases as the square of the speed, and it follows that the pressure should increase as the speed since the higher pressures are only needed when the speed is high. The piston being relatively heavy, and the centrifugal force being a substantial factor in the control of the pressure that is controlled, then a unit is provided that is adaptable for a wide range of speeds of operation,

and it follows that the components of control, centrifugal force and line pressure, will vary as the propeller is rotating at top speed or at some intermediate speed, yet the fluid circuit will always be safeguarded against reaching pressures over the predetermined 950 pounds per square inch.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A pressure control valve comprising in combination, a tubular casing having a pair of apertured ears for securement to a rotatable support, said casing having a main bore exposed to a source of pressure to provide a pressure chamber and communicating at one end thereof with a reduced bore, exhaust ports opening from the reduced bore, a piston slidable in the reduced bore and providing a pressure area exposed to the chamber pressure and adapted to slide axially of the casing for connecting 'the exhaust ports therewith, a piloting portion connected with the piston and having a head slidable along the larger bore of the casing, spring means disposed between the piloting portion and the reduced bore of the casing tending to maintain the piston valve closed by urging the piston to a position between the pressure chamber and the exhaust ports, an integrally joined head member for the casing,r to provide a fluid tight damping chamber at the end of the piloting portion, and a restricted passage in the pilot portion connecting the damping chamber with the pressure chamber of the casing whereby movement of the piston in either direction along the casing bore is damped by the ow of fluid to and from the damping chamber.

2. The combination set forth in claim 1, wherein the area of the valving piston is equivalent to a relatively small area of the head of the piloting portion.

3. The combination set forth in claim 1, wherein a porting sleeve fixed within the casing provides the reduced bore, and the pressure control valve is assembledthrough the open end of the casing before the porting sleeve is affixed.

4. The combination set forth in claim 1 wherein one end of the casing is tted with a porting sleeve providing said reduced diameter bore, and wherein a cylindrical passage between the casing and porting sleeve is included to provide an -annular chamber into which the exhaust ports empty for elimination of frothing.

5. A pressure control valve comprising in combination, a. tubular casing having an integrally closed end and laterally extending mounting lugs intermediate its ends, an intake port to the bore of the casing remote from the open end thereof, exhaust ports diametrically disposed at the open end of the casing, a piston with stepped heads movable lengthwise of the casing, one of said heads being slidable in the bore of the casing at the normally closed end thereof to provide a damping chamber, a restricted passage through said head connecting the damping chamber with the bore of the casing, a porting sleeve disposed in the open end of the casing having a smaller bore concentric with the bore of the casing, and adapted to slidingly receive the smaller of the stepped piston heads, said sleeve having an annular groove constantly communicating with the exhaust ports of the casing, and cross passages connecting the groove with the .bore of the sleeve, and spring means disposed between the larger head of the piston and the porting sleeve tendingv to diminish the volume of the damping chamber, and normally urging the smaller head to a position between the porting sleeve inlet and the exhaust ports, the smaller of the stepped piston faces dening an area subject to the pressure exerted through the intake port for opposing the spring movement of said piston.

6. A pressure control valve comprising in combination, a casing having a cylindrical bore with an integrally closed end wall, means connecting the bore with a fluid pressure source, a porting sleeve secured in the open end of the bore providing a concentric bore of reduced diameter for reception of a valving piston, cross passages through the casing and sleeve opening the bore of the sleeve to the outside of the casing, resilient seal means disposed between the sleeve and casing, a valving piston slidable lengthwise of the vcasing and having a damping head guided at the closed end thereof so as to provide a damping chamber, a restricted flow passage traversing the head so as to connect the damping chamber and the cylindrical bore, and a valve head slidable lengthwise of the porting sleeve to connect and disconnect the cross passage of the sleeve with the bore of the casing, a compression spring disposed between the damping head and porting sleeve tending to urge the damping head against the closed end of the casing and to adjust the valve head to a position on the high pressure side of the cross passages of the porting sleeve, said valving piston being reduced in diameter adjacent lthe valve head to permit free ow when the piston is situated on the low pressure side of the cross bores of the sleeve.

CHARLES S. J. MAcNElL. JOHN F. HAINES. RICHARD E. MOORE. HOWARD CARSON.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES v PATENTS Number Name Date 2,080,824 Kane May 18, 1937 2,103,299 Ravnsbeck Dec. 28, 1937 2,307,102A Blanchard et al Jan. 5, 1942 2,327,830 Stevenson Aug. 24, 1943 2,391,699 Haines Dec. 25, 1945 FOREIGN PATENTS Number Country Date 113,329 Australia of 1941 703,319 Germany Mar. 6, 1941 

